| 摘要 |
PURPOSE:To increase the torque compensating amount at low speed time of a DC motor by providing a peak value fork and a circuit for reference level setting or the like. CONSTITUTION:A capacitor C2 forming a peak value fork circuit PF is charged through a diode D7 by the speed feedback voltage of a motor M as detected by a transistor Q1, and a resistor R0 graudally discharges the capacitor C2 during the conducting period of the transistor Q2 in which no divided voltage Vn is generated from the speed feedback voltage. Accordingly, the fluctuation of the voltage Vn does not exert an affect to the input voltage to a comparator COMP, and the voltage across the capacitor C2 is supplied through a reference level setting circuit Rc to the COMP. Since the transistor Q5 of the circuit RC exhibits an impedance substantially equal to zero when the voltage across the capacitor C2 is zero, the reverse feedback voltage level can be arbitrarily set by selecting the values of the resistors R10, R11. Accordingly, it can increase the torque compensating amount at low speed time. |
